The Muscular System

With your host…Arnold Schwarzenegger

What do muscles do?

• Muscles move you! Without muscles you couldn't open your mouth, speak, shake hands, walk, talk, or move your food through your digestive system. There would be no smiling, blinking, breathing.

• Muscles turn energy into motion. (Think of all the things you do that you need your muscles for! It would be impossible for you to do anything without your muscles!)

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Did you know…?

If all 600+ muscles in your body pulled in one direction, you could lift 25 tons!!!

That’s about the weight of THREE African Elephants!

Types of Muscles

Smooth muscles

• Also called involuntary muscles (Your brain and body tell these muscles what to do without you even thinking about it.)

• Located in your internal organs.• Examples: in diaphragm, walls of

digestive organs.

Cardiac muscle

• Found only in the heart.• Cardiac muscle is striated, like

skeletal muscle.

Skeletal Muscle• Also called voluntary muscle.

(They only work when you specifically tell them what to do).

• These are the muscles that we can see, feel, and control.

• Make up 50% of your body weight.• Examples: bicep, tricep.

What's the job of skeletal muscle?

• Body movement• Posture• Body heat• Communication

Major Skeletal Muscles

How do you move?• You move because pairs of muscles

work together.– When one muscle of a pair contracts,

the other relaxes.•Flexor - muscle that flexes, or

bends a joint•Extensor - muscle that extends, or

straightens a joint– Muscles always pull!

Other muscle knowledge…

• Over time, muscles can become larger or smaller, depending on whether or not they are used.

• Blood carries energy-rich molecules to the muscles so they can do their work.

Let’s Review…